Incidence and Outcomes of Acute Laryngeal Injury After Prolonged Mechanical Ventilation

Abstract

Objectives: Upper airway injury is a recognized complication of prolonged endotracheal intubation, yet little attention has been paid to the consequences of laryngeal injury and functional impact. The purpose of our study was to prospectively define the incidence of acute laryngeal injury and investigate the impact of injury on breathing and voice outcomes.

Design: Prospective cohort study.

Setting: Tertiary referral critical care center.

Patients: Consecutive adult patients intubated greater than 12 hours in the medical ICU from August 2017 to May 2018 who underwent laryngoscopy within 36 hours of extubation.

Interventions: Laryngoscopy following endotracheal intubation.

Measurements and main results: One hundred consecutive patients (62% male; median age, 58.5 yr) underwent endoscopic examination after extubation. Acute laryngeal injury (i.e., mucosal ulceration or granulation tissue in the larynx) was present in 57 patients (57%). Patients with laryngeal injury had significantly worse patient-reported breathing (Clinical Chronic Obstructive Pulmonary Disease Questionnaire: median, 1.05; interquartile range, 0.48-2.10) and vocal symptoms (Voice Handicap Index-10: median, 2; interquartile range, 0-6) compared with patients without injury (Clinical Chronic Obstructive Pulmonary Disease Questionnaire: median, 0.20; interquartile range, 0-0.80; p < 0.001; and Voice Handicap Index-10: median, 0; interquartile range, 0-1; p = 0.005). Multivariable logistic regression independently associated diabetes, body habitus, and endotracheal tube size greater than 7.0 with the development of laryngeal injury.

Conclusions: Acute laryngeal injury occurs in more than half of patients who receive mechanical ventilation and is associated with significantly worse breathing and voicing 10 weeks after extubation. An endotracheal tube greater than size 7.0, diabetes, and larger body habitus may predispose to injury. Our results suggest that acute laryngeal injury impacts functional recovery from critical illness.

Trial registration: ClinicalTrials.gov NCT03250975.

Figure 1;. Mechanism of intubation-induced laryngeal injury:

The tongue base drives the endotracheal tube into the posterior glottis and direct pressure results in laryngeal mucosal and soft tissue injury at the endotracheal tube interface.

Figure 2;. Long-term breathing and voice outcomes:

Sixty seven patients (70% with and 63% without acute laryngeal injury) completed outcome questionnaires with both the surveyor and patient blinded to endoscopic findings during hospital admission. Clinical COPD Questionnaire (CCQ): Red dashed lines represents mild COPD (lower line; CCQ ≥ 1) and severe COPD (upper line; CCQ ≥ 2.5). Voice Handicap Index-10 (VHI): Red dashed line represents the minimal clinical significance (VHI ≥ 4). Wilcoxon rank sum test p=0.005 for VHI and <0.001 for CCQ.

Figure 3;. Association of endotracheal tube size with gender, body mass index, and intubating provider:

Predicted log odds of selecting a larger size endotracheal tube from an ordinal regression model (proportional odds model) investigating the association of endotracheal tube size with gender, body mass index, and intubating provider. The log odds values were adjusted to male, body mass index = 30.2, and emergency department personnel. These results confirm the general practice among doctors—males and larger patients are intubated with larger endotracheal tubes. However, anesthesia and emergency medical service providers used smaller tubes, while critical care specialists and emergency department physicians tended to use larger endotracheal tubes. Y-axis: log odds of larger endotracheal tube size placement (7.5 vs 7.0 or 8.0 vs 7.5 tubes). Ans = Anesthesia; CCT = Critical care team; ED = Emergency department physicians; EMS = Emergency medical service; OSP = Other/Outside personnel. Body Mass Index = kg/m².